Prevailing torque locknut

ABSTRACT

An all-metal prevailing-torque locknut having two substantially equally spaced, arcuate indentations in its top endface. The endface indentations displaces the two adjacent circumferentially aligned internal threads both radially inwardly and axially downwardly and also give the adjacent threaded bore an ovular configuration.

United States Patent [1 1 Frailly 1 June 26, 1973 [5 4] PREVAILING TORQUE LOCKNUT 1,967,276 7/1934 Wilson 151/21 13 [75] Inventor: Robert Adam Frailly, Massillon,

Ohio Primary Examiner-Edward C. Allen [73] Assignee: Eaton Corporation, Cleveland, Ohio Attorney-Howard Gordon 22 Filed: Nov. 22, 197i 57 [21] Appl. No.: 200,95Q 1 ABSTRACT An all-metal prevailing-torque locknut having two substantially equally spaced, arcuate indentations in its top (gl. endface. The endface indentations displaces the two ja circumferentiany aligned internal threads [58] Field of Search 151/21 B, 21 C both radially inwardly and axially downwardly and also {56] Reierences Cited give the adjacent threaded bore an ovular configurat UNITED STATES PATENTS 206,566 7/1878 Hemelright l5l/2l C 2 Claims, 3 Drawing Figures PREVAILING TORQUE LOCKNUT BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to all-metal prevailing-torque locknuts and more particularly to prevailing torque locknuts utilizing a novel indentation construction to deform a portion of the internal threads and the threaded bore.

2. Description of the Prior Art Several types of all-metal prevailing-torque locknuts utilizing various types of indentation or other forms of deformation are known in the prior art. However, the prior art Iocknuts have not been totally satisfactory in that they have generally failed to meet the recognized (Industrial Fasteners Institute) standards for both reuseability and for locking or resistance to forces tending to cause loosening or backoff such as vibrations.

BRIEF SUMMARY OF THE INVENTION The present invention overcomes the drawbacks of the prior art to the extent that an all-metal prevailingtorque locknut is provided which meets or exceeds the recognized standards both for reuseability and resistance to loosening and backoff. The above is accomplished by providing a locknut having two equally circumferentially spaced arcuate indentations in its top endface. Each indentation is in the form of a segment of a circle which is generally concentric with the threaded bore of the locknut and each segment extends circumferentially for approximately I 10,and is spaced circumferentially by approximately 70 from the other segment. The indentation segments are so formed as to distort the two adjacent circumferentially aligned threads both axially downwardly andradially inwardly. The indentation structure utilizing two 110 segments of threads with distortion or locking threads, separated by 70 segments of relief or resilient areas has been found to provide a novel prevailing-torque locknut which meets or exceeds the generally accepted standards of reuseability and locking properties.

An object of the present invention is to provide an all-metal prevailing torque locknut having adequate holding torque after repeated applications.

Another object of the invention is to provide a lock- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of the nut before concerting the nut into a locknut.

FIG. 2 is a vertical sectional view of the completed locknut illustrating the distorted threads in elevation.

FIG. 3 is a top view of the completed locknut of the present invention as viewed from line 3-3 of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION The nut l, illustrated in FIG. 1, and the locknut l0 fonned therefrom, illustrated in FIGS. 2 and 3, are of a hexagonal outer configuration comprising a nut body 11 having six flats or sidewalls l2 and a top and a bottom endface, 13 and 14 respectively. The nut body 11 is provided with a threaded through bore 15 which is coaxial with the hexagonal cross-section of the nut.

The locknut 10 is formed by subjecting nut l to a staking operation wherein indentations or grooves 16 are formed by a staking tool shown in phantom lines in FIG. 2. The grooves 16 so formed are generally V- shaped having an angle-of approximately 45 with respect to the vertical closest the bore and an angle C of approximately 4 8 with respect to the vertical furthest the bore. It has been found that the above V shaped pattern allows for a thread deformation, as at 17, of the two adjacent threads, 17a and 17b respectively, circumferentially aligned with the grooves which is both axially downwardly and radially inward. It has been found that deforming the second 17b as well as the first 17a adjacent thread provides a locknut of excellent operational characteristics. The bore adjacent the indented endfaces also gives a generally ovular configuration. j The grooves 16, when viewed from endface 13, are of a semicircular or arcuate configuration and are equally circumferentially spaced by undepressed areas. The angle B in FIG. 3 indicates the circumferential angle of unindented space separating the grooves. It is to be carefully noted that the threads 17 adjacent and circumferentially aligned with the indentation grooves 16 are deformed while the threads 18 circumferentially aligned with the unindentedarea are notdeformed. It is this section 18 of undeformed threads which acts as a relief or resiliency area to provide reuseability'while the deformed threads 17 are the threads providing locking action. The undeformed threads 18 allow the deformed threads 17 to behave as springs for both locking and reuseability qualities. I

Experimentation has indicated that an indentation angle A of -l20 with an unin'dented angle B of 90-60 is a workable range for relative circumferential length of the indented and unindented areas with a preferred angle A of about and a preferred angle B of about 70 for optimization of desired locking and reuseability qualities.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction may be resorted to without departing from the spirit'and the scope of the invention as hereinafter claimed.

I claim:

1. A prevailing torque locknut maintaining substantially constant torque during repeated on/off applications comprising:

a nut body having a plurality of substantially flat sidethreaded I bore downwardly and radially-inwardly resiliently deformed along their thread portions adjacent to and circumferentially-aligned with said grooves and the portions of said two threads circumferentiallyaligned with the unindented end face being substantially free from deformation, the uppermost thread deformed more than the other.

2. The prevailing torque locknut of claim 1 wherein said included angle is approximately 1 10. 

1. A prevailing torque locknut maintaining substantially constant torque during repeated on/off applications comprising: a nut body having a plurality of substantially flat sidewalls; an upper and lower end face and a threaded bore therethrough; said upper end face having two substantially arcuate, equally circumferentially-spaced grooves indented therein and concentric with said threaded bore; said grooves circumferentially spaced from one another to define an included angle from the axis of said bore and between the ends of said grooves in the range of 90*- 120* and said grooves further defined by downwardly-extending converging walls with the wall of said grooves closest said threaded bore, forming an angle of approximately 45* with the vertical and the wall distant said bore forming an angle of 6* - 8* with the vertical; and said threaded bore having its uppermost two threads at said upper end face portion of said nut axially-downwardly and radially-inwardly resiliently deformed along their thread portions adjacent to and circumferentially-aligned with said grooves anD the portions of said two threads circumferentiallyaligned with the unindented end face being substantially free from deformation, the uppermost thread deformed more than the other.
 2. The prevailing torque locknut of claim 1 wherein said included angle is approximately 110*. 